Simulation is an area of computer graphics that places high demands on the ability to generate lifelike images, sometimes as close to an actual photograph as possible, and also to be able to do so as quickly as possible or using the least amount of system resources. A particular challenge in simulation is to generate a plausible appearance—and in animated sequences, behavior—of granular materials, for example sand or dust.
Granular materials occur in many contexts and have characteristics that vary according to the situation but also some characteristics that are common despite the exact nature of the granular material. A fine-grained material like dust or flour is going to behave differently from sand or pebbles, but they have in common that the particles making up the material are to some extent homogeneous within a range of sizes and shapes, and that the material have the ability to form stable piles, unlike a liquid material.